Although no records setting the date of first work on DMAD Dam are available, the Soil Conservation Service engineered the current geometry. Construction on this dam began late in 1959 and was completed in 1960. During State of Utah mandated Phase II dam safety studies, several issues related to dam safety were evaluated and included in a plan to bring the dam into compliance with State of Utah dam safety requirements. Major items included were: (1) stabilizing the main dam downstream toe to minimize risks of damaging slope failure during major seismic events, (2) installing a 20-foot deep drain (below ground-water levels) at the downstream toe, and (3) draining/stabilizing a seepage area near the reservoir outlet to Canal A.
We performed field work, laboratory testing, analytical studies and evaluations and developed plans and specifications for this work. An additional phase of work will include evaluating the ability of the current spillway to safely pass the State of Utah mandated inflow design flood.
Field work also indicates that liquefiable materials are present in foundation soils beneath the existing spillway, which might detrimentally affect performance of the spillway during major seismic events. Studies are currently underway to evaluate risks associated with this possible condition, and costs that might be associated with stabilizing spillway foundation materials.
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